bFloatPointRenderTarget=1 must be set in SkyrimPrefs.ini file to make this mod work. Start SkyrimLauncher.exe to configure your video options again.
To work correctly, sky lighting require rendering objects to shadow, so edit manually following lines in file SkyrimPrefs.ini:
bTreesReceiveShadows=1
bDrawLandShadows=1
bShadowsOnGrass=1